The invention relates to an air flap supply device for the controlled supply of burner air to a combustion engine, wherein the damper flap is adjusted using at least one retraction unit.
A device of the type mentioned above is known from WO 95 35 440 A2. The drive by wire system disclosed therein consists of a damper flap unit and a positioning unit that are arranged together in one housing. The damper flap unit includes at least one damper flap, positioned within the housing, and connected to a damper flap shaft. The positioning unit consists of a motor unit, a retraction spring and an opener spring, that are connected at the damper flap shaft such that a vehicle can be moved during normal operation and in the limp home operation in case of a malfunction of the motor unit.
DE 36 31 283 A1 discloses a device for the controlled, metered addition of burner air to a combustion engine that allows for an emergency driving operation and prevents a freezing of the damper flap in the idle position in case of a malfunction of the electrical positioner connected to the damper flap. The damper flap is connected to a positioning shaft. Also connected to the positioning shaft are a retraction spring and a counter spring. While the retraction spring positions the damper flap in an end position, the counter spring ensures a damper flap is opened at an idle angle enabling an emergency driving operation.
A device with a similar design as the one mentioned above, and that also employs two springs, is known from EP 0 992 662 A2.
Common to these three solutions is the utilization of helical springs, which are susceptible to breakage. In addition, helical springs provide a spring force that increases exponentially.
DE 41 40 353 A1 discloses a device for adjusting the airflow through a flow-through element, with a damper flap, for a fuel supply system of a motor vehicle with an internal combustion engine. A spring is located in a housing. At the outset, the spring has a helical shape, and describes an angle of 300xc2x0. The first, helical section of the spring changes to a second, U-shaped section. The spring exhibits a second end at the end of the U-shaped section. The spring counters the rotary motion of the electric motor. Its design ensures that the damper slide valve retains a small opening for emergency operation in case of a malfunction of the electric motor.
Finally, DE 41 24 973 A1 describes a load adjustment device for a drive motor, where a damper flap may be held at an adjustable stop outside of the regular flap position range, when desired. However, the spring to be employed is a tension spring, a compression spring or a torsion spring.
The present invention provides an air flap supply device with a damper flap element connected to a damper flap shaft element, in the damper flap opening, and adjustable therein by a positioning movement (G) using at least one retraction unit, comprising a magnetically homo-polar counter movement unit.
The advantages achieved with the invention arise especially from the use of magnetic spring elements, used in place of a spring element. The magnetic spring element is break-proof and its spring travel path can be adjusted such that it is essentially linear during its motion. This results in a better and more accurate positioning capability.
A first counter movement unit can be designed such that at least two magnet elements, with the same magnetic polarity are arranged opposite to one another, in such a manner that they may be moved toward each other along an arc. Such a retraction unit, replacing the conventionally employed retraction spring, always moves the damper flap element to a secure end position.
The first magnet element of the first counter movement unit, may be a holding magnet element positioned at a magnet holding peg in the damper flap housing element. The second magnet element of the counter movement unit, may be a moving magnet located on at a magnet support arm of a sprocket unit that is connected to the damper flap shaft element.
The holding and the moving magnet elements can move in one or two planes. The spring characteristic and the spring force can be influenced in this manner.
The counter movement unit can exhibit a third magnet element that can be arranged at the moving magnet element with an opposite magnetic pole, which acts as an amplification magnet element.
In the spring travel path, the holding magnet element and the moving magnet element can be located with their south poles opposite to one another. However, it is also possible that their north poles are located opposite to one another. The counter spring movement along the spring travel path can essentially be rising linearly.
The amplification magnet element can be arranged with its south pole at the north pole, or with its north pole at the south pole, of the moving magnet element. These measures ensure that during a movement of the moving magnet element to the holding magnet element, a magnetic force is established in opposition to this movement, where said magnetic force has the same retracting effect as a spring force.
The moving magnet element and the amplification magnet element can be molded, at least partially, into the magnet support arm. The magnet support arm and an adjacent sprocket segment of the sprocket unit may consist, at least partially, of synthetic material. This allows for accurate positioning and easy embedding of the two magnet elements in the magnetic support arm.
A second counter movement unit may be designed such that at least two additional magnet elements with the same magnetic polarity are arranged at least partially offset above one another and slideable in relation to one another. This retraction unit replaces the limp home spring, enabling an emergency operation of the air flap system in case the motor drive unit malfunctions. In addition, this construction avoids the possibility of the damper flap element freezing in one position.
A standing magnet element can be attached within a magnet housing unit, that is supported by an additional support plate, the standing magnet element being the first magnet element of the second counter movement unit.
A slide magnet element, positioned offset to, and above, the standing magnet element is a second magnet element of the counter movement unit, and is moveable into the magnet housing element using a stop arm of an additional sprocket unit that may be connected to the damper flap shaft element.
A repelling magnet element can be located in the stop arm. This increases the spring force.
The sliding magnet element and the standing magnet element can be separated into a north pole and a south pole (N, S) located opposite to it; exhibit a disc-shaped north pole around which at least one south pole is located; or exhibit a disc-shaped north pole with a disc-shaped south pole opposite to it.
The holding magnet element, the moving magnet element, the shaft magnet element and the standing magnet element, the first, second and third sliding magnet element and the first, second and third standing magnet element can have a cross-section that is square, rectangular, triangular, quadrangular, multi-angular, oval, round, elliptic or the like. The motion characteristic of this magnet structure can be influenced in this manner.
The first, second and third sliding magnet element may be burred at opposite sides. In this manner, the sliding magnet element can be moved in a torsion-proof manner.
The moving holding magnet element, the moving element, the shaft magnet element and the standing magnet element can be permanent magnets. Known magnetic materials may be used as the magnet materials if the present invention.
Thus, it is a principal objective to advance an air flap supply device of the type mentioned above such that its damper flap element can be adjusted easily and securely.
For a full understanding of the present invention, reference should now be made to the following detailed description of the preferred embodiments of the invention as illustrated in the accompanying drawings.